add mollie plugin

plugins/mollie/lib/foodsoft_mollie.rb

@@ -0,0 +1,35 @@
+# require 'Mollie/API/Client'
+require 'mollie-api-ruby'
+require 'foodsoft_mollie/engine'
+
+module FoodsoftMollie
+  # Enabled when configured, but can still be disabled by +use_mollie+ option.
+  def self.enabled?
+    FoodsoftConfig[:use_mollie] != false and FoodsoftConfig[:mollie]
+  end
+
+  # Compute payment transaction fee.
+  #
+  # Transaction fee is specified in foodcoop config under +mollie+, +fee+ as a
+  # hash of fee per payment method, e.g. as "0.30" for a fixed flat fee, "5%"
+  # for a percentage, or "0.30 + 5%" for both. Multiple flat fees and percentages
+  # can appear in a single line, so "0.12 + 2% + 0.56 + 3% + 1%" is valid, e.g.
+  # when multiple payment providers add different fees.
+  #
+  # @param amount [Number] Amount payed
+  # @param method [String] Payment method used
+  # @return [Number] Transaction fee for payment, or +nil+ if no fee details known.
+  def self.payment_fee(amount, method)
+    spec = FoodsoftConfig[:mollie]['fee'] or return
+    unless spec = spec[method]
+      Rails.logger.warn "Mollie: transaction fee for method #{method} not configured."
+      return
+    end
+    # parse
+    return spec if spec.is_a? Numeric
+
+    spec.split('+').inject(0) do |sum, c|
+      sum + (c =~ /^(.*)\s*%\s*$/ ? (::Regexp.last_match(1).to_f / 100 * amount.to_f) : c.to_f)
+    end
+  end
+end

plugins/mollie/lib/foodsoft_mollie/engine.rb

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+module FoodsoftMollie
+  class Engine < ::Rails::Engine
+  end
+end

plugins/mollie/lib/foodsoft_mollie/version.rb

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+module FoodsoftMollie
+  VERSION = "0.0.1"
+end